A. Field of the Invention
The present invention relates to a method and device for providing telephone subscribers access to computer networks. In particular, the present invention relates to providing digital telephone lines the ability to direct telephones calls to a computer network or service such as an Internet Service Provider ("ISP").
B. Description of the Related Art
Telephone service may be provided by a digital telephone line or Digital Loop Carrier ("DLC") system such as carried by a 1.544 Mbps T1 digital line allowing a number of different telephone subscriber lines to be multiplexed over a single set of copper wire telephone cable. The use of DLC systems enables a significant reduction in the amount of cable required to provide telephone service to subscribers. Rather than installing 24 separate pairs of copper wire between each subscriber location and the telephone company CO, 24 different subscriber lines can be time-division multiplexed onto a single connection of wires at a Remote Data Terminal ("RDT"). All 24 telephone connections can therefore be carried from the RDT to the telephone company central office ("CO") on a single set of wires. Thus, using a DLC system, only a single set of wires must be installed from the telephone central office to the RDT, and the full complement of 24 pairs of wires need only be run from the RDT to the subscribers' telephones. The reduction in copper facility required allows telephone service to be provided more cost effectively.
Today, an increasing number of telephone subscribers use their telephones to access a computer network such as the Internet. To access the computer network, computer users utilize a computer modem to establish a telephone connection over the Public Switched Telephone Network ("PSTN") to a dial-up telephone line providing access to the computer network. The PSTN is any of the networks, usually carrying telephony voice, fax, and modulated digital computer data, provided by AT&T, GTE, Regional Bell Operating Companies and other communication networks comprising multiple switching offices.
The dial-up access telephone line is typically connected to a Private Branch eXchange ("PBX") which switches telephone calls to a Remote Access Server ("RAS") providing telephone dial-in access to the computer network from the PSTN. The RAS typically includes a plurality of modems to receive incoming telephone calls from the PSTN telephone lines or trunks and a plurality of Network Interface Cards ("NICs") providing access to the desired computer network. The RAS interfaces and connects the plurality of modems to the plurality of NICs providing access to the computer network. A telephone call to access a computer network thus originates at an originating switching office, may be sent through the PSTN via one or more intermediate switching offices, to an end switching office, a PBX, and then to the RAS. At the end office, the incoming calls are received from the PSTN by the PBX and terminated to the RAS to provide access to the computer network.
There are a number of problems associated with using the PSTN to provide a data connection to access to a computer network such as the Internet or an intranet. A telephone connection routed through the PSTN passes through multiple switching offices, an end switching office, possibly a PBX, and then to the RAS to provide access to the computer network. Such transmission of data signals through multiple switching offices may require the signals carried by the telephone connection to be converted between various transmission formats through each switching office, significantly degrading the signal at each conversion and reducing its ability to accurately carry computer information. The routing of telephone calls through multiple switching offices in the PSTN may degrade the quality of the transmitted signal and reduce the bandwidth carrying capability of the connection. Thus, a device and method for proving a connection to the RAS without routing the telephone call through multiple PSTN switching offices is desirable.
The present invention address the problems of providing access to a computer network for telephone subscribers serviced from a DLC.